Report: Advanced GIS - Creating Land Use Map for the City of Galveston, Texas

Term Project

Land Use Map for the City of Galveston, Texas PLAN 262, Spring 2010

Travis Scott and Avinash Shrivastava

Table of Contents Introduction .............................................................................................................................................. 1 Methodology ............................................................................................................................................. 1 Data Collection and Management ........................................................................................................ 1 Data Comparison .................................................................................................................................. 4 Parcel Conflict Resolution ..................................................................................................................... 5 Final Map .................................................................................................................................................. 6 Limitations................................................................................................................................................. 6 Findings/Analysis ...................................................................................................................................... 7 Land Use Analysis .................................................................................................................................. 7 Descriptive Spatial Analysis ................................................................................................................... 7 Density Analysis .................................................................................................................................... 8 Network Analysis: Service Area ............................................................................................................ 8 Network Analysis: Closest Facility ......................................................................................................... 9 Network Analysis ‐ Transit Routes ...................................................................................................... 10 Recommendations .............................................................................................................................. 10 Monitoring and Updates ......................................................................................................................... 11 Conclusion ............................................................................................................................................... 12 References .............................................................................................................................................. 13 Appendix ................................................................................................................................................. 14 Appendix A – Land Use Map ............................................................................................................... 14 Appendix B – Analysis Maps ............................................................................................................... 14

Land Use Map for the City of Galveston, Texas

Introduction The creation and utilization of a land use map is critical in the comprehensive planning process.

Land use maps provide information on the activity being performed on the land. The activity identifies the purpose each piece of land serves and how humans are using it.1 By creating a land use map, a land use analysis can be performed. Land use analyses helps identify incompatible uses or problems areas that require policy actions to correct them. These incompatible land uses can be based on environmental concerns (i.e. development in the flood plain) or human use concerns (i.e. industrial uses near residential areas). Land use analyses also provide information to planners on land supply and land that is developable (Berke, Godschalk, Kaiser, & Rodriguez, 2006). This is important for planning projected growth of the city. A land use analysis provides an evaluation of the spatial distribution of land uses which is useful in the creation of land use policy intended to shape the growth of the city.

A land use map was developed for the City of Galveston in order to provide the data needed to conduct land use analyses. This map will serve as an important aspect of the comprehensive plan and provide necessary baseline data for future planning.

Methodology Data Collection and Management

The first step in the analysis was data collection. Below is a list of the data obtained for this

analysis. 

GIS Parcel data from the County Appraisal District (shapefiles)



Landmarks from County Appraisal District (shapefiles)



o

Government

o

Hospital

o

School

o

Park

City of Galveston GIS data (shapefiles) o

Cemeteries

o

Churches

o Colleges

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RMURP Chapter 6 page 273 1

Land Use Map for the City of Galveston, Texas

o

Liquor Stores

o

Parks

o

Schools

o

Overlay Zoning

o

Subdivisions

o

Zoning Districts



City of Galveston land use permit data (spreadsheet data)



May 2009 high resolution aerials created by the General Land Office

The most recent County Appraisal District (CAD) parcel data, September 2009, was used as the baseline data for this analysis as it represents a complete count of the parcels located within the county. This data also includes a land use identification code for each parcel. Data outside of the Galveston city limits was removed from the dataset and from analysis. This data, being used as the baseline for analysis, was to be compared to each other source of data for inconsistencies in land use identifications. In order to compare each “layer” of data, a common classification system needed to be created.

The process of creating a land use classification specifically for Galveston began with a literature review of three sources; the American Planning Association’s publication, “Land‐based classification standard” (American Planning Association, 1999), Chapter Six of the book “Research methods in urban and regional planning” (Wang & Hofe, 2007), and the City of Austin’s Land Use Methodology website found at: http://www.ci.austin.tx.us/landuse/survey.htm. These sources offer quality guidance as well as insight into highly complex land use classification methodologies.

The level of detail for this analysis, number of and depth/hierarchy of land use classifications, was determined based on the information available in the existing data while taking into account the direction from the above references. The most detailed and comprehensive land use data was found in the CAD parcel data, which included 24 different land use types. These land use codes are listed and described below:

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Land Use Map for the City of Galveston, Texas

Code Description

Code Description

A1

Single Family Residential

D5

Acreage Non‐Qualifying Ag

A2

Single Family Mobile Home

D9

Acreage Exempt

A3

Single Family Condo

E1

Farm and Ranch Improvements

A9

Exempt

F1

Commercial

B1

Multi Family Residential

F2

Industrial

B2

Multi Family Duplex

F9

Commercial Exempt

B9

Multi Family Exempt

J1

Utilities Water

C1

Vacant Platted Lots Residential

J2

Utilities Gas

C9

Vacant Platted Lots Residential Exempt

J3

Utilities Electric

D1

Acreage Ranch Land

J4

Utilities Telephone

D4

Acreage Undeveloped

O1

Inventory Vacant

O2

Inventory Improved

Utilizing the methodology from the literature referenced above, these categories were aggregated down to land use categories appropriate for a final land use map. The information found in the remaining data layers was then utilized to add finer detail to the final land use classifications.

The remaining CAD data consists of a GIS shapefile layer which contains geographic coordinate locations (X, Y data) for “landmarks” with specific land uses attributed to each landmark. This data includes a variety of land uses including government properties, schools, parks and Hospitals. The City of Galveston also provided a series of GIS layers identifying individual parcels of different land uses. These uses include; cemeteries, churches, colleges, liquor stores, parks, and schools. Overlay zones and subdivision shapefile layers from the city were also researched to determine if they could offer insight into the specific land uses based on the regulations for each subdivision or zone. It was found that these two layers lacked the specificity needed to specifically identify and cross check individual parcel land uses. The final GIS shapefile layer analyzed from the city was the zoning districts. Regulations for each zone were summarized into allowable land uses and this data was used as the final dataset to be cross checked against the land use map. The final dataset used to cross check land uses of each parcel is recent land use permit data where some land use information is noted for each permit. This data was also obtained from the City of Galveston.

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Land Use Map for the City of Galveston, Texas

From the data discussed above, the final list of land use classifications determined for this analysis is below.

1

Single‐Family Residential

9

Recreation/Parks

2

Multi‐Family Residential

10

Government

3

Residential other

11

Hospital

4

Commercial

12

Vacant

5

Heavy Industrial

13

Cemetery

6

Light Industrial

14

Transportation

7

Agricultural

15

Religious

8

School

16

Open Space

Data Comparison This list of land use classifications was used to reclassify each of the datasets discussed above in order to perform cross checks across each overlapping dataset. This was done by creating a new field to every dataset. In this new field, the newly assigned classification for each parcel or location was placed. All GIS shapefiles were reclassified in this manner using the exact same text to ensure accurate cross checking between layers. Once every layer was reclassified, the data was put together in ArcGIS. Cross checking the data layers was performed by comparing each layer’s classification to the base layer (parcel) data. This process was done by performing joins with each data layer, attribute selecting out the mismatched parcels, and using “field calculator” to add “mismatched” in a new field to all parcels with discrepancies between data layers. The Mismatched field represented all parcels that had discrepancies. Each parcel with conflicting land use data was also marked to indicate which specific data layers did not match. This provided quick reference to the parcels with discrepancies, and an easy way to see which data layers did not match.

During the process of joining and reclassifying, it was noted that there were multiple copies of attribute data for each parcel in the original parcel data. This became problematic as data was joined together. Joins were performed based on “XREF” codes, or unique identifier codes for each parcel. During the joins, the duplicated parcel attributes were joined together with the matching parcel attributes (which were also duplicated) which resulted in exponentially multiplying the attributes for each parcel. Duplicate data was duplicated again and again creating even more duplicate data. To solve this problem, the parcels that contain Xref data (many parcels have a blank xref) were dissolved using the “dissolve” tool in ArcGIS. This appended all of the duplicate 4

Land Use Map for the City of Galveston, Texas

attributes into a single attribute for each parcel. The remaining parcels which do not have xref data could not be dissolved as they would have been reduced to a single attribute. Instead, this data was manually added back into the new dissolved parcel dataset. This dataset then represented the final dataset. It has only a single attribute for each parcel and represents every parcel on the island.

Parcel Conflict Resolution The process verifying and correcting each parcel that was identified with conflicts was done using a series of methods. The data and methods utilized are listed below: 

May 2009 high resolution GLO aerial imagery



Parcel “name” attributes



Land use permit records from the city



Google Street View (with discretion)



In‐person site visits

The aerial imagery was the first data set used to assist in determining actual land uses for conflicting parcels due to the fact that it is high resolution, post‐Hurricane Ike, imagery that can both help to discern what is happening on each parcel and what the status of it is after Ike (whether it was demolished or destroyed). The parcel attributes “name” is the property owner’s name. This can help assess the land use. For example, if there is question whether a property is a public park or not, the owners name, which could be a church, the school district or the city, will shed light on its owner and therefore allow it to be correctly classified.

Land use permit data for the years 2008 through 2009 was also utilized in the conflict resolution as it includes a description of the land use for which each permit was given. Although there are often multiple permits and permit types given to each parcel, this data provides further evidence of what types of uses are happening on each parcel. This also provides insight into uses that have been happening in the post‐Ike setting.

Google Street View was utilized; however it was used with discretion. Due to the lack of information provided by Google about when the Street view imagery was taken, any information gathered from it cannot be utilized as definitive. This information was used more as a clue to the actual land use rather than a final solution to the land use. Site visits were the final method of solving parcel conflicts. For those parcels which the above information could not definitively solve, students visited the site to determine the actual land use as well as verify as many of the conflicting parcels as possible.

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Land Use Map for the City of Galveston, Texas

Final Map Once every parcel was corrected and classified using the new classification system, the dataset on which the final map is based was complete. This data contains attribute data for each parcel which includes the xref designation as well as a land use classification. Using the final, corrected, land use classifications, each parcel can be displayed on a map and colored based on each specific land use type. Combining the parcel data with other publically available data, for example transportation and water/ocean data, a final map was created within ArcGIS. This map was printed to PDF and imported into Adobe Illustrator where final presentation details were added to it. This final map is attached in Appendix A.

Limitations As discussed above, the final map is based mostly on the County Appraisal District land use designations and therefore adopts any problems or inconsistencies included in their data. Every other piece of information was compared to this layer of data. In the process of fixing cross checking parcels, several other parcels were noted as being labeled incorrectly in the CAD data.

Given the limited scope and time to perform both the analysis for the map and the land use analysis, we were unable to verify/check every parcel in the database for consistency. Throughout the project we made every effort to perform random checks of the CAD data for accuracy performed fixes on as many parcels as we could. Even with these efforts, there are likely still incorrect classification parcels in this dataset.

Additionally, some of the geometric shapes within the CAD database were also found to have some inconsistencies. For example, several parcels, marked as vacant, extend beyond the beach and well into the ocean while some parcels appear to be overlaid over multiple, seemingly older, parcels. It is beyond our scope to identify if parcels beyond the coast are to be removed however, in most cases the overlapping parcels were fixed/reclassified based on the process described above.

There may be a few subtle overlaps remaining which can be fixed during routine database maintenance.

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Land Use Map for the City of Galveston, Texas

Findings/Analysis Land Use Analysis After the preparation of the Land Use map, several analyses were performed. However, the data obtained was redundant and it was difficult to begin the analysis. The major trend that was evident by looking at the land use map was that facilities like schools, churches, parks, etc i.e. public amenities were clustered in the east end of the Galveston and not spread evenly across the island.

However, by observing the spread of the residential parcels throughout the Galveston Island, it was evident that there is a need for these facilities throughout the entire island, especially in the southwest region of the island.

Spatial analysis and network analysis were performed, using ArcGIS, to substantiate the validity of the assumption and look further into the implications of the trend.

Descriptive Spatial Analysis We began by determining mean center, central feature and directional distribution of the below mentioned features. The results were plotted on three different maps. (Refer Figures 1, 2 &3 in Appendix B) Figure 1:  Single Family Residential  Multi‐family Residential  All Parcels (Current)  Blockgroups (2000)  Population in 2000 (at the blockgroup level) Figure 2:  Schools  Churches  Parks  Green Areas Figure 3:  Commercial After performing this analysis and seeing the resulting maps, two noteworthy observations were noted. One is rather random; the other supports the trend discussed above. These included: 1. Change in Directional Distribution: In Figure 4 of Appendix B, it is clearly illustrated that the directional distribution of parcels at blockgroup level in 2000 was northeast‐ southwest.

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Land Use Map for the City of Galveston, Texas

Alternatively, the directional distribution of the parcel level data is north‐south. This indicates a change in the directional distribution of parcels/population of about ‐40 degrees from the year 2000 to the current distribution. The implications of this are not certain but it was an interesting trend worth noting.

2. Shift in the Mean Center: Since there was no data available on the current total population on the Galveston Island, mean center for residential parcels was plotted and compared to the total population data in 2000 (at blockgroup level). This map is shown as Figure 5 in Appendix B. It demonstrates that there is a shift in the mean center of the total population from northeast to southwest. This further bolsters the idea that the population, which has historically been clustered in the eastern portion of the island, is moving towards the southwest and spreading along Galveston Island.

To further support this analysis, detailed density analysis was performed for the following features (Refer Figures 6, 7, 8, 9, 10 & 11 in Appendix B), Figure 6: Population in 2000 (at blockgroup level) Figure 7: Residential (Single and Multi family) Figure 8: Commercial Figure 9: Parks Figure 10: Schools Figure 11: Churches

Density Analysis (Figures 6, 7 & 8) show that the residential and commercial uses are spread throughout the Galveston Island. However the spread is not evenly distributed or uniform, residential parcels are found clustered around the island.

Figures 9, 10 & 11 in the Appendix illustrate that facilities like parks, schools and churches are only found densely clustered in the eastern region of Galveston Island. This was the first substantial evidence that validated the mentioned above.

Network Analysis: Service Area Another important observation was that facilities like parks, schools and churches are densely clustered and located on the eastern portion of the island and do not serve the population across the entire island. The service area maps (Figures 12, 13 & 14 in Appendix B) show that the facilities like schools, churches and parks, though being densely clustered, lie beyond any of the ¼ or ½ mile walk‐sheds, and not even within a one mile service area of all the parcels in the west end

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Land Use Map for the City of Galveston, Texas

of the island. Hence, it was evident that these facilities were neither walkable nor easily accessible from all the residential parcels in the Galveston Island.

Network Analysis: Closest Facility To further support the above analysis, two random parcels in the western portion of the city, which do not lie in the ¼ or ½ mile walk‐sheds of the facilities like schools, churches and parks, were located on the map. Using another feature of ArcGIS 9 named ‘Closest Facility’, the distance of these two random parcels were measured from the nearest facilities located in the western portion of the island. It was found that most of the travel distances were greater than the ½ mile. This demonstrates that the location of most important facilities is neither strategic nor functional, especially in the western portions of the island. (Refer Figure 15 in the Appendix) One important land use which needs to be accessible is hospitals. The location of, and therefore accessibility of hospitals on the island, are by no means ideal as shown in Figure 16 in the Appendix. Here, one of the two randomly plotted parcels is about 4.7 miles from the nearest hospital, which is at the eastern end of the island. Figures 17 & 18 in the Appendix also show that the distance from the sample parcel to the hospital, after including barriers like schools, parks and churches in the route. This increases the travel distance to 5.6 miles.

To further illustrate these issues, a sample school was plotted in the western end of the city.

The distance from the nearest hospital and one of the two randomly plotted sample parcels was measured (Figures 19 & 20 in the Appendix). Implications of this are shown by examples. If an incident takes place at this school, the distance to the nearest hospital from the school is more than 3 miles (Figure 20). If the sample parcel is assumed to be the home of the kid attending this school, the distance from the school to the home is more than 2 miles (Figure 19). This illustrates that the distance to both these important destinations is greater than 2 miles. It was also observed that the shortest distance from these two randomly plotted parcels to a major commercial store ranges from 1 mile‐3 mile (Figure 21).

The above mentioned analysis clearly validates that the facilities in the western portions of the city and island, though being adequate, do not conveniently serve to all the population on the island.

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Land Use Map for the City of Galveston, Texas

Network Analysis ­ Transit Routes In order to analyze the efficiency and effectiveness of a transit route, for the residential parcels in the southwest region of the Galveston Island, another sample parcel was plotted on the far southwest end of the Island and its distance from the nearest school was measured. The distance was approximately 13 miles if the transit service runs directly from origin to the destination (Figure 22 in Appendix B).

If the same bus was to cater to all the residential parcels in the southwest region, and had bus stops every one mile or so, the number of stops would increase to approximately 56 bus stops and the distance would increase to 39 miles (Figure 23). Even if the transit routes were increased and improved, it would not be an effective and efficient solution to transportation on the western portions of the island. It might serve as a secondary solution, but it is not substantial enough to be a single solution. The primary and most effective solution would be to equally distribute important facilities like schools, churches, parks and hospitals around the island.

Recommendations The above mentioned analysis validates that there is a need for important facilities, like schools, churches, parks, hospitals, etc, to be spread evenly throughout the Island. It was also noteworthy that these facilities should also be strategically located in order to functionally serve the total population on the western half of the island.

On a more specific note, some of the schools and churches densely clustered at the eastern end of the island should be moved to the southwest and critical facilities like hospitals should be brought in to better serve the central and western portions of the island. (Refer to Figure 24 in Appendix B).

By using Density Analysis, the centers of population can be easily identified. This information can help strategically locate important facilities like schools, churches, parks, and hospitals. Network Analysis also supports the idea that strategic relocation of important facilities is the most effective and efficient solutions to making these facilities function and serve to the total population on the island.

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Land Use Map for the City of Galveston, Texas

Monitoring and Updates A land use map is not a static map that is printed and posted somewhere. Rather it is dynamic and constantly changing with what happens on the ground. Therefore, the data created by this project represents a base dataset from which the land use map should be maintained and updated.

Land uses change often and each change needs to be reflected in the land use data and in the resulting maps. In order to keep the land use map up to date, the City of Galveston will need to verify, maintain and update this dataset on a relatively constant basis. There are several ways that this can be done.

One method to maintain this dataset is to use construction permits which document the land use of each property which obtains a permit. These permits were used in the creation of this dataset and offer direct insight to what is happening on each parcel of land. Using GIS, this process can be streamlined by simply joining the permit data using the XREF codes and cross checking the land uses of both the existing GIS and the permit data. Then the existing data can be updated to match any changes on each specific parcel. This should be done on at least an annual cycle.

Other methods include simply keeping track of local developments and general progress throughout the city and constantly or regularly updating the database to reflect the changes as they come. Another method of maintenance includes performing spot checks on a regular basis is also needed to verify and fix any errors introduced by the County Appraisal District.

A combination of these methods would be the most preferred method. This is a large dataset and there are a large number of parcels to be verified and maintained. Therefore the City should utilize as many methods as possible to maintain the dataset and should consider finding additional methodologies to improve upon or add to these.

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Land Use Map for the City of Galveston, Texas

Conclusion

Land use maps represent important information for municipalities and can be used as a tool

for both current and future planning. As shown above, the implications of land use patterns and trends can be revealed with such a tool. Utilizing the information contained in, and the analysis which can be performed from it, a land use map can be used to assist in fixing apparent problems and guide positive changes within the build environment. Utilizing GIS in this process provides both the computing power and the analysis ability to detect these patterns, perform future trends analysis, and make better decisions.

Once the data has been compiled, simple maintenance and upkeep represents the work necessary to keep the data up to date. With proper maintenance, this land use dataset can continue to provide pertinent information in the process of planning and growth for the City of Galveston.

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Land Use Map for the City of Galveston, Texas

References American Planning Association. (1999). Land­based classification standards. Chicago, IL: American Planning Association.

Wang., X., & Hofe., R. v. (2007). Research methods in urban and regional planning. Beijing [etc.]: Tsinghua University Press [etc.].

Berke, P. R., Godschalk, D. R., Kaiser, E. J., & Rodriguez, D. A. (2006). Urban Land Use Planning.

Chicago, Illinois, United States of America: Journal of American Institute of Planners.

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Land Use Map for the City of Galveston, Texas

Appendix Appendix A – Land Use Map

Appendix B – Analysis Maps

Figure 1

14

Land Use Map for the City of Galveston, Texas

Figure 2

Figure 3

15

Land Use Map for the City of Galveston, Texas

Figure 4

Figure 5

16

Land Use Map for the City of Galveston, Texas

Figure 6

Figure 7

17

Land Use Map for the City of Galveston, Texas

Figure 8

Figure 9

18

Land Use Map for the City of Galveston, Texas

Figure 10

Figure 11

19

Land Use Map for the City of Galveston, Texas

NETWORK ANALYSIS SERVICE AREA ‘SCHOOLS’

Figure 12

NETWORK ANALYSIS SERVICE AREA ‘CHURCHES’

Figure 13

20

Land Use Map for the City of Galveston, Texas

NETWORK ANALYSIS SERVICE AREA ‘PARKS’

Figure 14

Figure 15

21

Land Use Map for the City of Galveston, Texas

Figure 16

Figure 17

22

Land Use Map for the City of Galveston, Texas

Figure 18

Figure 19

23

Land Use Map for the City of Galveston, Texas

Figure 20

Figure 21

24

Land Use Map for the City of Galveston, Texas

Figure 22

Figure 23

25

Land Use Map for the City of Galveston, Texas

Figure 24

26